AMQP-295 Fix Version in QuickStart

The <version/> element in the maven dependency
stanza in the quick start was obsolete.

Use newer version of gradle docbook plugin that
now supports replacing the ${version} placeholder
in files other than index.xml.

Update build.gradle to add the quick start chapter
to the 'expandPlaceholders' property.

Change quick start chapter to use the ${version}
placeholder.